1. Technical Field
The present invention relates to a liquid-ejecting head that includes a piezoelectric element, a liquid-ejecting apparatus, the piezoelectric element, and a piezoelectric material. The piezoelectric element includes a first electrode for altering the internal pressure of a pressure-generating chamber communicating with a nozzle opening, a piezoelectric layer, and a second electrode.
2. Related Art
One example of piezoelectric elements for use in liquid-ejecting heads is a piezoelectric layer between two electrodes. The piezoelectric layer is formed of a piezoelectric material having an electromechanical transfer function, such as a crystallized dielectric material. Such a piezoelectric element can be mounted on a liquid-ejecting head as an actuator in a flexural vibration mode. One representative example of liquid-ejecting heads is an ink jet print head. The ink jet print head has a diaphragm as part of a pressure-generating chamber, which communicates with a nozzle opening for discharging ink droplets. The diaphragm is deformed by a piezoelectric element to pressurize ink in the pressure-generating chamber, thereby discharging ink droplets from the nozzle opening. A piezoelectric element for use in such an ink jet print head can be produced by forming a uniform piezoelectric layer on the entire surface of a diaphragm by a film-forming technique and dividing the piezoelectric layer by lithography into pieces corresponding to each individual pressure-generating chamber.
The piezoelectric material used for such a piezoelectric element requires excellent piezoelectric characteristics (a large strain). One representative example of the piezoelectric material is lead zirconium titanate (PZT) (see JP-A-2001-223404).
However, from the standpoint of environmental protection, there is a demand for a piezoelectric material with little or no lead. Examples of a lead-free piezoelectric material include those having an ABO3 perovskite structure, such as BiFeO3. However, lead-free piezoelectric materials having an ABO3 perovskite structure produce a smaller strain than lead zirconium titanate. These problems are not confined to liquid-ejecting heads, including ink jet print heads, and occur in other piezoelectric elements.